Insulating material.



A. B. REYNDERS.

INSULATING MATERIAL.

APPLICATION FILED JULY e. 1908.

952,467. Patented Mar. 22, 1910.

WITNESSES:

, NVENTOR TTORNEY esaaea narran' estaras `remmer cuenten.

ARTHUR 3B. REEYIYDEBS, '0F WLKlINSBURG, iPENBTSYLVNIA, ASSlGNOR, BY MESNE SSKGNMSENTS, TG) TESTING-HOUSE ELECTRIC & MANUFACTURING COMPANY, OF EAST PIT'EBUB'G, DENN'SYLVANIA, CORPGRATGN OF PENNSYLVANIA.

NSULATING MATEREIAL Specification of Letters Patent.

Patented Mar. 22, illtti.

Application filed July 6, 190%. Serial N o. 442,195.

j of tVilkinsburg, in the county of Allegheny and State of Pennsylvania, have invented a new and useful improvement in insulating li/iaterials,` of which the following is a specication. j

My invention relates to insulators for high potential electrical circuits, and it has for its object to provide an insulating body in which the strains will be prevented from concentration upon or adjacent to outer snrfaces, but will be equally distributed throughout the thickness of the body.. j

The invention consists in constructing an insulator of alternate layers of suitable insulating and conducting materials, a series of condensers being thereby provided between the external surfaces of the insulator, whereby the the total strain to which the insulator is subjected is distributed throughout the thickness of the insulating material. insulation of this general type has beenused in the prior art and is known as condenser type insulation. When this insulation is utilized for bushings Vor sleeves for the electrical separation of conducting leads from the inclosing casings or tanks in which transformers and other electrical apparatus are contained, it has been found desirable to taper the ends of the cylindrical bushing, in order to increase the surface or .creepage distance between the conducting cylinders which constitute the condenser plates. The capacity of concentric cylinders is dependent upon the distance between them, which is equal to the 1diHerence between their radii, the specific inductive capacity of the insulation between them and the areas of their adjacent surfaces. course, desirable to reduce the size and the cost of the insulating bushings as far as it is possible to do so, and it has been found that these conditions can be best fulfilled by making the areas of the conducting cylinders which constitute the condenser plates,

. equal, andalso by keeping the distances between "the plates Vsubstantially equal but if it is attempted to construct a bushing which preferably fulfils the aforesaid conditions, it is found that the difference in the lengths j of the successive outer cylinders is very A 4slight while the difference between the For high voltage work, it is, of

lengths of the successive inner cylinders is considerable, so that the taper at the ends of the complete bushing is constantly varying and the surface distance between adjacent conducting plates near the outer surface is very short.

According to my present invention, I have overcome these difficulties by constructing a bushing having uniformly tapered ends and conducting cylinders which are equally spaced apart and by compensating for the inequality in the areas of the severalplates, so as to maintain the ideal condition of a ,series of condensers having equal capacities partiallyI in section, of an insulating bushing that embodies my invention.

in the drawing, a rod or bar l, of any suitable conducting material, which may constitute a circuit lead, is provided with an insulating bushing 2, byl which it is in su- 5I, lated from a metal casing or supporting bracket 3.

rlhe insulating bushing 2 is preferably constructed as set forth in Patent No. 858,385, granted July 2, 1907, to the "Westinghouse Electric & Manufacturing Company as assignee of Emil Haefely, sheets 4 of tinfoil or other suitable conducting ma-v terial being interposed at convenient or desirable intervals between the convolutions 5 of insulating material during the construction of the bushing. .The metallic sheets 4 form with each other and the conductor 1 a series of condensers in which the strains upon the insulation are proportional to the di'erences of potential between the sheets.`v

LIF.)

are unitorrnly distributed 'throughout its thickness, which is reduced to a nfiinimum7 and at the same time an equal surface distance or creepage distance is maintained hetween the ends ot the conducting cylinders.

l't will be readily umile'rstood7 by those skilled in the art, that the utilization of poorer grades of insulating material for a material part of the construction of the insulating bushes considerably reduces the total expense involved in its manufacture.

l claim as my invention:

l. An insulating structure, comprising alternate layers of insulating material and conducting material which constitute a series ot condensers, the insulating layers being graded as to specific inductive capacity in accordance with their distances from the surfaces of the structure.

2. An insulating structure comprising a plurality ot alternate layers ot conducting material and insulating material, the specltic inductive canacity ot the intermediate insulating layer or layers being less than that of the outside and inside insulating layers of the structure.

3. An insulating bushing comprising a plurality of concentric conducting cylinders and va plurality ot insulating cylinders, which alternate in position with said conducting cylinders, the speciic inductive esami plurality of concentric conducting cylinders and a plurality oit insulating cylinders which alternate in position with said conducting cylinders, the specic inductive capacity of the outside and inside insulating cylinders being relatively high., and the specitic inductive capacity ot the intermediate insulating cylinders being relatively low.

An insulating bushing having tapered ends and comprising a plurality of concentric cylinders of conducting material separated by insulation and constituting a series of condensers. the insulation between the intermediate cylinders being of lower specilic inductive capacity than the insulation hetween the cylinders near the inner and outer surfaces ot the bushing, whereby an equality in capacity of the condensers is effected.

ln testimony whereof, l have hereunto subscribed my name this 18th day ot dune, 1908.

ARTHUR B. REYNDERS.

lWitnesses 0. C. Emmaus, Brenna* Hines. 

